#include<iostream>
#include <cstdio>
#include <string.h>
using namespace std;
int main()
{
	int n,cnt = 0;
	cin>>n;
	char a[50],b[50];
	double temp,sum = 0.0;
	for(int i = 0; i < n; i++){
		scanf("%s",&a);
		sscanf(a,"%lf",&temp);
		sprintf(b,"%.2f",temp);
		int flag = 0;		
		for(int j = 0; j < strlen(a); j++)
			if(a[j] != b[j]) flag = 1;
		if(flag || temp > 1000 || temp < -1000){
			printf("ERROR: %s is not a legal number\n", a);
            continue;
		}
		else{
			sum += temp;
			cnt++;
		}
	}
	if(cnt == 1)
        printf("The average of 1 number is %.2f", sum);
    else if(cnt > 1)
        printf("The average of %d numbers is %.2f", cnt, sum / cnt);
    else
        printf("The average of 0 numbers is Undefined");
    return 0;
}
